1. Field of the Invention
The present invention relates generally to a field emission device having an emitter formed in a nano hole, and more particularly to a field emission device and a method of fabricating the same which can lower the operating voltage to reduce the power consumption.
2. Description of the Prior Art
Field emission devices employ a phenomenon that electrons are emitted from a part of the emitter when a voltage is applied between the emitter and a gate electrode. The field emission devices are applied to microwave devices or field emission displays (FED).
Generally, the field emission device is divided into a diode-type having an upper plate and a lower plate used as an emitter and a cathode, and a triode-type having a gate formed around an emitter for supplying a voltage.
As the diode-type has a high operating voltage and is difficult to control the amount of electron emission, the triode-type is usually employed. In particular, a spindle type emitter is widely used.
The spindle type emitter has a fine tip of a cylindrical shape and emits electrons when a high electric field is applied to an end of the fine tip. Thus, as the operating characteristic of the spindle type emitter is stable, it has been most widely used as an emitter of the triode-type field emission device. Further, a lot of researches on the shape and material of the tip have been actively made.
As the field emission device having this spindle type emitter, however, is driven with a high voltage of about 50Vxcx9c100V, it has a high consumption voltage. Thus, it is required that the voltage be further lowered in order to commercialize the field emission device using the spindle type emitter.
In order to fabricate a field emission device driven with a low voltage, an aspect ratio of the emitter must be increased. Therefore, a research on manufacturing the emitter using carbon nanotube has recently been made.
FIG. 1 is a cross-sectional view of a conventional field emission device.
Referring now to FIG. 1, an emitter electrode 12 made of metal is formed on a silicon substrate 11. An insulating layer 15 having an aperture 15a is formed on the emitter electrode 12. A catalyst layer 13 made of a transition metal is formed on the emitter electrode 12 exposed through the aperture 15a. An emitter 14 is formed on the catalyst layer 13. A gate electrode 16 having a given pattern is formed on the insulating layer 15. The transition metal includes carbon nanotube, a nano grain film and a metal tip.
At this time, the emitter 14 composed of a metal tip may be formed right on the emitter electrode 12 exposed through the aperture 15a without the catalyst layer 13.
If an operating voltage is applied to the emitter electrode 12 and the gate electrode 16, respectively, a high electric field is formed around the emitter 14. Due to this, electrons are emitted from the emitter 14.
Meanwhile, in order to fabricate the field emission device driven with a low voltage, it is required that the aspect ratio of the emitter be increased. The aspect ratio of the emitter can be increased by a formation of a hole having a nanometer size. The hole having a nanometer size should be formed in anodized aluminum oxide layer since the hole can not be formed in conventional oxide layer. However, anodized aluminum oxide is not suitable for the semiconductor manufacturing process. Therefore, it is difficult to manufacture the emitter having a large aspect ratio by using the conventional method.
The present invention is contrived to solve the above problems and an object of the present invention is to provide a field emission device and a method of fabricating the same, capable of reducing the driving voltage and thus lower the power consumption, in such as way that a hole having a nanometer size is formed by processes of manufacturing the semiconductor devices and an emitter is then formed in the hole to increase the aspect ratio of the emitter.
In order to accomplish the above object, a field emission device according to the present invention, is characterized in that it comprises a silicon substrate having an emitter electrode formed in a surface portion thereof; an insulating layer formed on the emitter electrode and having a nano hole to expose the emitter electrode; an emitter formed on the emitter electrode exposed through the nano hole; and a gate electrode formed on the insulating layer.
A method of fabricating a field emission device according to the present invention is characterized in that it comprises the steps of forming silicon rods on a silicon substrate; forming an emitter electrode within the silicon substrate; forming insulating layer between the silicon rods; forming a gate electrode on the insulating layer; forming a nano hole in the insulating layer by removing the silicon rods; and forming an emitter on the emitter electrode exposed through the nano hole.